Being playing for a month now after a 1.5 years hiatus.

Totally subjective status of tanks from my experience:

WAR: Self healing machine. Lots of mits.
GNB: Decent mits, quite decent DPS.
PLD: Lots of resources for any situation. Decent mits.
DRK: I have a sword. Big one. That's it.

Seriously what have they done to DRK? Almost non viable as tank, boring to play and end of DPS and mitigation spectrum. TBN does not fix it. It is the BARe minimum to be a tank, though a very ill performing one.